Slasher Teams

Does anyone have any advice on how I can improve my slasher team (better units)? I currently have mihawk, arlong, zoro, kuro, tashigi, morgan, and buggy (all of them are evolved to the max). Right now I'm using 2x mihawk, arlong, zoro, kuro, and tashigi. Should I switch any of the units out for another unit I already have?

It depends on who you are fighting against. For morgan right now your crew is perfect, but without any specific goal i would change out tashigi for buggy, because he gives a variety of types. 
Better units will come with time, for example on the next story isle there will be Mr3 as a farmable character. He is a better version of buggy as a int slasher and comes with a one turn delay. Really good support slasher in my opinion.

Mystogan is right. Various colors of Characters are better. I also cant wait for Mr. 3.

^^